Device for accommodating disk-shaped objects and apparatus for handling objects

ABSTRACT

A device for receiving plate-shaped objects, preferably semiconductor wafers, for the thermal treatment thereof, enabling the processing of wafers made of connecting semiconductors in a particularly simple manner. The inventive device offers high productivity and low risk of damage as a carrier has at least two recesses for respectively receiving an object. The recesses on the carrier can preferably be provided with covers. Preferably, support pins are provided for loading and unloading purposes. The carrier and the support pins can move in a vertical direction in relation to each other. A handling device for objects is also disclosed.

[0001] The present invention relates to a device for accommodatingdisk-shaped objects, preferably semiconductor wafers, for the thermaltreatment thereof. The invention also relates to a handling apparatusfor objects.

[0002] For the industrial manufacture of electronic components,semiconductor materials having a disk-shaped configuration, so calledwafers, are subjected to thermal treatments. Especially the thermalprocessing of objects, such as wafers, by means of rapid heating units,also known as RTP units (Rapid Thermal Processing) is continuously beingemphasized. The main advantage of RTP units is their high throughput,which is based upon the possibility of being able to very rapidly heatup the wafers. Heating rates of up to 300° C./s can be achieved in RTPunits.

[0003] An RTP unit essentially comprises a transparent process chamberin which a wafer that is to be processed can be disposed upon suitablesupport devices. Furthermore, in addition to the wafer, diverseauxiliary elements, such as, for example, a light-absorbing plate, acompensation ring that spans the wafer, or a rotation or tilting devicefor the wafer can be disposed in the process chamber. The processchamber can be provided with suitable gas inlets and outlets in order tobe able to produce a prescribed atmosphere within the process chamber inwhich the wafer is to be processed. The wafer is heated by a thermalradiation that issues from a heating device that can be disposed eitherabove the wafer or below the wafer or on both sides, and is composed ofa plurality of lamps, rod or point-type lamps, or a combination thereof.The overall arrangement can be surrounded by an external chamber, theinner walls of which are entirely or at least partially reflective.

[0004] In alternative RTP units, the wafer is placed upon a heatingplate or susceptor, and is heated by a thermal contact with thissusceptor.

[0005] With connecting or combination semiconductors, such as III-V orII-IV semiconductors, such as, for example, GaN, InP, GaAs or tertiarycompounds such as, for example, InGaAs or quaternary compounds such asInGaAsP, there is, however, the problem that generally one component ofthe semiconductor is volatile and upon heating of the wafer evaporatesout of the wafer. There results predominantly in the edge region of suchwafers a heating zone with a reduced concentration of the evaporated-outcomponent. The result is an alteration of the physical characteristics,such as, for example, the electrical conductivity, of the wafer in thisregion, which can make the wafer unusable for the production ofelectrical components.

[0006] From the two publications U.S. Pat. No. 5,872,889 A and U.S. Pat.No. 5,837,555 A, which originate with the applicant, it is known todispose wafers of combination semiconductors in a closed receptacle ofgraphite for the thermal treatment. Due to its stability at hightemperatures, graphite is particularly suitable for such receptacles.The wafer is placed upon a support that has a recess for accommodatingthe wafer. Placed over the recess is a lid-like cover, so that a closedspace results in which the wafer is disposed. This graphite receptaclein which the wafer is contained is subjected to a thermal treatment inthe process chamber of an RTP unit. In this way, a diffusing-out of acomponent of the combination semiconductor is suppressed, and the wafercan be safely processed.

[0007] The described graphite receptacle is predominantly used forprocessing wafers of a combination semiconductor having diameters of 200mm and 300 mm. However, very common are also wafers of combinationsemiconductors having small diameters of 50 mm, 100 mm, or 150 mm.

[0008] It is an object of the present invention to provide a device withwhich wafers of combination semiconductors can be safely processed in asimple manner and at high productivity.

[0009] Pursuant to the invention, this object is realized by a carrierhaving at least two recesses for respectively receiving a wafer. Withsuch carriers, a plurality of wafers can be processed simultaneously. Incontrast to the known treatment methods, this means a considerableincrease of the throughput of an RTP unit, and represents a significanteconomical advantage.

[0010] Pursuant to one particularly advantageous embodiment, theinventive device has at least one cover for covering at least one recessin order to provide an essentially closed-off space about the objects.

[0011] For example, a single large cover is possible that covers all ofthe recesses of the carrier with the wafers contained therein. However,alternatively each recess could also be covered by individual covers. Itis also possible that one of the covers simultaneously covers anydesired number of recesses, although more than one and not all of them,or any desired number of the recesses can be individually covered andthe remainder of the recesses can remain uncovered. Such a cover can becombined in any desired manner with other similar covers as well as withindividual covers for a respective recess and with non-covered recesses.

[0012] The carrier that is provided with the recesses is preferably madeof graphite, sapphire, quartz, boron nitride, aluminum nitride, silicon,silicon carbide, silicon nitride, ceramic or metal. Similarly, at leastone of the covers can be made of graphite or sapphire or quartz or boronnitride or aluminum nitride or silicon or silicon carbide or siliconnitride or ceramic or metal. However, not only the carrier but also atleast one or all of the covers can also be made of the aforementionedmaterials.

[0013] For RTP processes, advantageously carriers are used having atleast one cover that has a low specific thermal capacity, preferably 0.2to 0.8 J/gK, of the carrier and/or of at least one cover. For thisreason, the carrier should have as low a thickness as possible.

[0014] Similarly, carriers having at least one cover are advantageouswhere the carrier and/or at least one of the covers has a high thermalconductivity, preferably 10 to 100 W/mK.

[0015] At least parts of the carrier, or parts of one of the covers, orparts of the carrier and parts of one of the covers, are preferablycoated. For example, it can be advantageous to at least partiallyprovide an inner surface of one or of all of the recesses, as well as asurface that covers the recess of one or more of the covers, with acoating that is inert to chemical processes that take place within thecovered recesses during the processing of the wafer, whereas externalsurfaces of the carrier remain uncoated in order to have desiredabsorption characteristics relative to the thermal radiation. In othercases, for example local optical characteristics of carrier and coverscan be achieved by suitable area wise coatings of the outer surfaces.

[0016] Similarly, it can be advantageous to make at least parts of thecarrier, or parts of at least one of the covers or parts of the carrierand parts of at least one of the covers, transparent for the thermalradiation by making them, for example, of quartz or sapphire. Thecovers, as well as parts of the carrier that correspond to the basesurfaces of the recesses, are advantageously nontransparent for thethermal radiation, while the other parts of the carrier are transparent.

[0017] It is furthermore possible to produce predetermined atmosphereswithin covered recesses. Depending upon the type of wafer that is to beprocessed, a different atmosphere can exist in each covered recess. Forexample, if in at least one first recess a InP wafer is processed, aphosphorous-containing atmosphere exists in the recess. In at least onesecond recess in which a GaAs wafer is to be processed, anarsenic-containing atmosphere exists. Finally, in at least one third,optionally not covered recess a wafer can be processed that comprisessilicon, in other words not a combination semiconductor.

[0018] At least some of the wafers accommodated by the carrier can be atleast partially coated. However, the volume material of at least one ofthe wafers can also vary in zones in that the wafer is provided, forexample, with an implanted layer.

[0019] The inventive carrier for a plurality of wafers, which aresubjected to a thermal treatment in common in a process chamber, makesit possible during the same process stage to achieve different processresults with the same course of the thermal radiation for each wafer.Depending upon the coating or transparency of local regions of thecarrier and/or of the corresponding cover, locally different opticalconditions can be achieved that lead to different temperatures in theinterior of the covered recesses. Thus, each wafer experiences anindividual process temperature, although the course of the thermalradiation is the same for all wafers. Thus, with one processing stage itis possible not only to simultaneously treat a plurality of wafers, butin so doing the wafers can even be subjected to different processes.This means that wafers of different materials can be treatedsimultaneously.

[0020] The recesses in the carrier preferably have the same depth, sothat after loading of the carrier the wafers are all disposed paralleland in the same plane.

[0021] However, it can also be advantageous to vary the depths of therecesses. In this case, although the wafers are always disposed parallelto one another, they are offset with respect to height and are disposedat different planes.

[0022] For cylindrical recesses having flat horizontal bases, the wafersrest flat on the base of the recess.

[0023] A support of the wafers within at least one recess isadvantageously selected, whereby a contact between wafer and the base ofthe recess is avoided. This is advantageously achieved by pin-shapedsupport elements that are disposed in the recess and which accommodatethe wafer. With the same depth of the recesses but different lengths ofthe support elements, the wafers can then be disposed at planes ofdifferent heights.

[0024] Another preferred possibility of arranging the wafers such that acontact with the base of the recess is avoided is to support the rimportion of the wafer. This is achieved by making at least one recess sothat it tapers conically inwardly. In this way, an inwardly beveled edgeof the recess is obtained that leads to a rim support of a wafer.Pursuant to another embodiment, at least one recess has a concaveconfiguration that again leads to supporting the rim of the wafer on theedge of the recess. Depending upon the design of the conical and of theconcave recesses, the wafer can be placed at different heights.

[0025] To load the carrier, the wafers are advantageously sequentiallyplaced via a gripper directly into the recesses or onto support pins.Suitable for this purpose are grippers having suction devices that drawthe wafers against them. This can be effected via a suction device thatoperates according to the Bernoulli principle.

[0026] Support pins are advantageously provided for the loading of thecarrier and preferably extend through the carrier. These support pinsadvantageously have different heights for different recesses in ordernot to obstruct a loading of the recesses that are remote from thegripper by the support pins that are provided for loading the recessesthat face the gripper.

[0027] Similarly, the covers can be placed upon support pins that eitherextend through the carrier or are disposed entirely externally of thecarrier. The support pins for the covers are advantageously longer thanthe support pins for the wafers.

[0028] The support pins and the carrier are preferably verticallymovable relative to one another.

[0029] As soon as the wafers are placed upon the support pins, thesupport pins move downwardly through the carrier, as a result of whichthe wafers are raised from the support pins and are deposited in therecesses associated with them. Alternatively, the carrier could also bemoved upwardly.

[0030] Another preferred method for loading the carrier sequentiallyrotates the carrier about a vertical axis in order to respectivelyrotate the recess that is to be loaded to the gripper.

[0031] As soon as the carrier is loaded with the wafers, thecorresponding covers can either be place directly upon the carrier orupon support pins by the gripper if they were not already placed uponappropriate support pins prior to the wafers.

[0032] A loading of the carrier is preferably effected within theprocess chamber. However, it can also be loaded externally of theprocess chamber and can subsequently be introduced into the processchamber for the thermal treatment.

[0033] A plurality of such carriers with covers can, for example,advantageously be stacked one above or next to each other within aprocess chamber for a thermal treatment.

[0034] The loading and unloading of the carrier with the substratesand/or covers is preferably effected with an automatic loading andunloading unit which can be appropriately controlled in correspondenceto the loading and unloading processes.

[0035] The inventive device is preferably, although not exclusively,particularly suitable for wafers of combination semiconductors havingpredominantly small diameters. The thermal treatment of thesemiconductor wafers is preferably effected in RTP units in whichprescribed environmental conditions and temperature profiles can be set.In this connection, during the treatment the carrier is extensivelystable at the environmental conditions and the temperatures.

[0036] Semiconductor wafers, especially combination semiconductorwafers, as they were previously described, are relatively thin and havethicknesses of 50 to 500 μm, and customarily 200 μm. These wafers aretherefore very susceptible to breakage during the handling, so that withthe conventional handling by hand or with handling apparatus, such asrobots and the like, breakage of the wafers frequently occurs, thusconsiderably reducing the yield during the manufacture of thesemiconductors. Especially with semiconductor wafers that are used forexpensive components, such as, for example, laser diodes, this isparticularly evident, since a two-inch wafer for this purpose has avalue in the range of

25,000.

[0037] As already indicated previously, the wafers are treated inreceptacles that are made, for example, of graphite and are introducedinto a process chamber for the treatment of the wafers. These so-calledgraphite boxes have a weight of 200 to 2,000 g, depending upon thenumber and the size of the wafers that are to be accommodated in theboxes.

[0038] Not only the wafers but also the receptacles themselves aremanually handled with such units, since with conventional handlingapparatus it is not possible on the one hand to handle the very thinsemiconductor wafers that have a weight in the range of 0.1 to 20 g, andon the other hand to handle the receptacles that in contrast are heavy,without having a high reject rate due to breakage of wafers.

[0039] It is therefore furthermore an object of the present invention toprovide a handling apparatus with which objects having different weightscan be securely and reliably handled.

[0040] Pursuant to the invention, the stated object is realized with ahandling apparatus having at least one transport arm, which in turn hasat least one support device for supporting, via vacuum, at least oneobject that is to be handled, by a vacuum control device for alteringthe vacuum as a function of the weight of the object.

[0041] Due to the inventive feature of providing a vacuum control devicevia which the vacuum of support devices on the transport arms can beset, controlled or regulated as a function of the weight of the object,it is now possible to transport and handle, with one and the samehandling apparatus, objects having very different weights. For example,with the inventive handling apparatus it is possible to undertake thehandling and the transport of wafers and wafer receptacles whileavoiding manual handling, and in particular in such a way that on theone hand, for example, relatively heavy receptacles can be handled withthe same handling apparatus as are the very thin, breakable wafershaving a low weight while avoiding breakage of the wafers. The inventivehandling apparatus thus enables, for example, not only the loading andunloading of receptacles into or out of the process chamber, but alsothe loading and unloading of the thin, breakable wafers into and out ofthe receptacle. Aside from the fact that in so doing the possibility ofa complete automation of the processing of semiconductor wafers,especially also in conjunction with thermal treatments, is provided,this takes place with a single handling apparatus, so that equipmentcosts can thereby be kept low. With the process automation that hasbecome possible with the inventive handling apparatus, the productionyield is significantly increased since breakage of wafers, as frequentlyoccurs during manual loading and unloading of the receptacle and of theprocess chamber, is avoided or at least significantly reduced. Atreatment unit having the inventive handling apparatus is thereforeamortized considerably earlier than are conventional treatment units dueto the low rejection rate and the rapid and reliable handling,especially if the unit is used for manufacturing very expensivecomponents.

[0042] Pursuant to one preferred embodiment of the invention, the vacuumcontrol device includes only one vacuum source and vacuum change-overdevices, for example line change-over switches, for switching between aline with and without a vacuum regulator. In this way, only one vacuumsource is required, whereby the vacuum regulator is preferably anadjustable valve. Pursuant to an alternative embodiment, at least twoseparately controllable vacuum systems are provided.

[0043] Pursuant to one advantageous embodiment of the invention, thepressure ratio for the objects that are to be handled and that havedifferent weights is in a range of from 10 to 10,000. This vacuum ratiois essentially a function of the weight ratio of the objects that are tobe handled and also of the design of the support devices.

[0044] Pursuant to a very advantageous embodiment of the invention, anobject having a low weight is a silicon semiconductor wafer, and anobject having a greater weight is a receptacle in which the wafers aredisposed during at least one treatment step. Receptacles of this typehave been described previously by way of example.

[0045] Although the support devices for objects having different weightscan be embodied in the same manner, it is, however, advantageouspursuant to a further embodiment of the invention to also embody thesupport devices differently for the different objects, especially forobjects having different weights. The support devices are preferablyso-called pads or support cushions that are connected via a line with avacuum source or a vacuum system. The individual support devices or padscan be supplied with the same vacuum, or they can also be supplied withrespectively different vacuums, which in this case, however, requiresappropriate control elements, such as, for example, valves or separatevacuum systems.

[0046] In this connection, the support devices are preferably adapted tothe objects having different weights, for example also to the shape andsurface structure of the objects. For example, for supporting thereceptacle generally larger support surfaces are required than forsupporting the light wafers. For example, it is advantageous for wafersto select the diameter of the support devices or pads to beapproximately 3 mm, or the surface upon which the vacuum acts per pad tobe approximately 0.1 cm². The shape of the pads is to be selected inconformity with the prescribed requirements, and it can be round orrectangular or have some other configuration. However, the pads arepreferably round, since here the ratio surface/rim is the greatest, andin so doing even at a low suction power of the vacuum source a reliableholding of the object, for example the wafer, is ensured.

[0047] So that a wafer having a weight of, for example, 0.1 g to 0.5 gcan be reliably held, the contact pressure produced by the pads, and viawhich the wafer is pressed against the support, must be great enoughthat the frictional force resulting from the contact pressure is greaterthan the forces produced by acceleration of the transport arm or theacceleration due to gravity, which act upon the object, for example thewafer. With wafers this is achieved, for example, via a vacuum ofapproximately 0.005 bar (this corresponds to an absolute pressure of0.995 bar), if the (horizontal) acceleration forces acting upon thewafer are less than 1 g. In this connection, one must take into accountthe frictional coefficient between wafer and support, which can again bea function of wafer temperatures.

[0048] If the vacuum is greater, i.e. the absolute pressure smaller, thewafer will still always be reliably held, in other words, theacceleration force can exceed 1 g, although there then exists the dangerof wafer breakage.

[0049] In general, the pad pressure that is to be selected is to beadapted to the maximum acceleration that occurs, as a result of which itis advantageous if the pressure is preferably controllable orregulatable. A vacuum that is too great is to be avoided. The adaptationof pressure can be effected not only prior to the start of the movementsequence but also during the movement itself. The maximum permissibleacceleration of the wafer is a function of the thickness of the waferand its diameter, the material and the type of wafer surface in thesupport region, in other words, also whether or not a structured orunstructured support region is provided.

[0050] If wafers having unstructured support regions are handled, anarrangement of the pads at approximately {fraction (2/3)} of the waferradius-relative to the center of the wafer-is preferably selected. Inthis way, the wafer is supported in a manner that is as free of stressas possible. With structured support regions, the pads preferablysupport the rim region of the wafer.

[0051] The inventive handling apparatus is preferably provided with athree-point support device for the object having greater weight and/orfor the object with lesser weight.

[0052] As already indicated, in this connection the support devices forthe different objects, and in particular those having different weights,preferably have different configurations.

[0053] The support devices for the objects that in particular differwith regard to their weight can both be disposed on one side of thetransport arm. Pursuant to a particularly advantageous embodiment of theinvention, however, support devices are provided on both sides of thetransport arm. This makes it possible to hold the objects that are to behandled during the handling process on the upper side or on theunderside of the transport arm depending upon the given conditions.Pursuant to a further embodiment of the invention, it is particularlyadvantageous if there is provided on one side of the transport armsupport devices for the heavier object and on the other side supportdevices for the lighter object. The one side, for example the upperside, has a first support or pad structure or support surface structure,for example for supporting receptacles, while on the underside of thetransport arm there is provided a second support or pad structure, forexample for supporting the wafer. For example, the wafer is held frombelow and the receptacle from above, or vise versa. With such anembodiment of the inventive handling apparatus, it is also possible toeliminate a vacuum control and to operate both support devices with thesame vacuum, since the holding forces are determined or codetermined bythe differing pad structures, especially the differing surfaceconditions. In addition, the frictional coefficients of the supportsurfaces can differ from above and below.

[0054] Pursuant to a further very advantageous embodiment of theinvention, the transport arm is rotatable by 180° relative to itslongitudinal axis.

[0055] As a result, the side with the support device adapted to acorresponding object can be rotated upwardly or downwardly.

[0056] Pursuant to a further embodiment of the invention, at least twotransport arms are provided, of which at least one is provided forsupporting a heavier object and at least one further one is provided forsupporting a lighter weight object. In this way, the support devices arerespectively provided on their own transport arm separately from oneanother for the respective different objects.

[0057] Pursuant to a further advantageous embodiment of the invention,the vacuum control device can be controlled as a function of aprescribed program sequence. Alternatively or in addition to thispossibility, it is particularly advantageous if a sensor, for example awire strain gauge, is provided for measuring the weight of the objectthat is to be handled. The result of this weight measurement, in otherwords the output signal of the sensor, is subsequently utilized forcontrolling the vacuum control device. In this connection, the sensorcan be provided directly on the transport arm or it is, however, alsopossible to first slightly raise the object, the weight of which is tobe determined, whereby the support pressure for supporting the object isdetermined as a measure for the weight of the object. By determining itsindividual weight, the object is reliably held during the movement. Withthis individual support pressure, the object is then moved. In additionto the actual support pressure, it is also possible to select or set themaximum acceleration, a selection of a previously fixed trajectory ofthe object, the speed or some other movement parameter. In this way, itis also possible to control so-called edge grippers that grasp the rimof the object, for example a wafer or a box, and fix the object at therim in order to achieve a localized fixing of the object in positionrelative to the handling apparatus. Such a firm holding can be effected,for example, mechanically, wherein the term “holding pressure” is alsoto be understood to mean a mechanical contact pressure of mechanicalparts of the handling apparatus against the object.

[0058] The present invention will be explained in greater detailsubsequently with the aid of preferred embodiments of the invention inconjunction with the drawings, in which:

[0059]FIG. 1 is a schematic cross-sectional illustration through a rapidheating unit;

[0060]FIGS. 2a) and 2 b) show a carrier for accommodating up to sevenwafers, in plan and in cross-section along the section line indicated inFIG. 2a);

[0061]FIG. 3a) to 3 f) show various embodiments of the cover of recessesin the carrier;

[0062]FIG. 4 shows two illustrations of alternative combinations ofrecess with wafer and cover;

[0063]FIG. 5 shows various embodiments for recesses;

[0064]FIG. 6 shows a mechanism for the loading and unloading of thecarrier;

[0065]FIG. 7 shows a schematic illustration of a transport arm of aninventive handling apparatus in plan;

[0066]FIG. 8 shows a side view of the transport arm illustrated in FIG.7;

[0067]FIG. 9 shows the schematic illustration of an embodiment of avacuum control device;

[0068]FIGS. 10a) and 10 b) show schematic illustrations of a transportarm, which is rotatable about it longitudinal axis, in plan from aboveand below.

[0069]FIG. 1 schematically shows a typical unit 1 for the rapid thermaltreatment of objects, preferably disk-shaped semiconductor wafers 2. Thewafer 2 is placed upon a holding or support device 3 which can, forexample, be pin-shaped support elements or a device upon which the waferis peripherally disposed, or some other type of wafer support. Thewafers 2, including the support device 3, are disposed in the interiorof a process chamber 4. The process chamber 4 is a transparent chamberthat is preferably manufactured at least in part of transparent quarts.Not indicated are inlets and outlets for process gases by means of whicha gas atmosphere that is suitable for the process can be produced.Mounted above and/or below and/or to the side—the latter not beingindicated here—of the process chamber 4 are banks of lamps 5 and 6.These are preferably a plurality rod-shaped tungsten-halogen lamps thatare disposed parallel to one another; However, other lamps could also beutilized. Alternative embodiments of the chamber eliminate either theupper bank of lamps 5 or the lower bank of lamps 6 and/or the laterallydisposed lamps. By means of the electromagnetic radiation emitted fromthe lamps, the object 2, for example a wafer, is heated. The entirearrangement can be surrounded by an external furnace chamber 7, theinside of the walls of which can be at least partially provided with areflective surface, and they can preferably be made of a metal such assteel or aluminum. Finally also present is a measurement device, whichpreferably comprises two non-contact measurement devices 8 and 9. Themeasurement devices 8 and 9 are preferably two pyrometers; however, CCDmonitors or sensors, or other devices for registering radiation, canalso be used.

[0070] In order to be able to successfully thermally treat connectingofrcombination semiconductors in such a unit, the semiconductors must beenclosed in a container in order to counteract a decomposition of thesemiconductor material. FIG. 2a) illustrates in plan a preferred rounddisk-shaped carrier 10. FIG. 2b) shows a cross-section through thecarrier 10 along the dot-dash line in FIG. 2a).

[0071] The carrier 10 has a plurality of circular recesses 11 to 17 ofthe same diameter in an upper disk surface 18 for respectively receivinga wafer. However, different diameters for the recesses are alsopossible. In this connection, one recess 12 is centrally disposed in thecarrier 10, while the remaining six recesses 11, 13, 14, 15, 16 and 17surround the central recess 12 along a circle that is concentric to thecentral recess 12 and to the edge of the carrier. The diameter of thecarrier 10 is preferably 200 mm, and the diameter of the same sizerecesses is preferably 52 mm.

[0072] The carrier 10 is preferably made of graphite, sapphire, quartz,boron nitride, aluminum nitride, silicon, silicon carbide, siliconnitride, ceramic or metal. The upper side 18, as well as the underside19 of the carrier, are advantageously finely blasted with glass beads inorder to ensure an optical homogeneity on the upper side 18 and on theunderside 19.

[0073] To obtain closed containers or receptacles for the wafers 3deposited in the recesses 11 to 17, the latter are provided with atleast one cover, which can also be finely blasted with glass beads. InFIG. 3a), all of the recesses 11 to 17, with the wafers containedtherein, are covered by means of a large cover 20. In another preferredform of the cover shown in FIG. 3b), the recesses 11 to 17 areindividually provided with covers 21 to 27. In FIG. 3c) the recesses 14and 13 are covered by the cover 28, the recesses 11 and 17 are coveredby the cover 29, and the recesses 15, 12 and 16 are covered by the cover30. FIG. 3b) shows an alternative form of the cover, where one of thecovers can simultaneously cover an arbitrary member of recesses, howevermore than one and not all of them. Here the recesses 15, 12, 16, 11 and17 are covered by the cover 31, and the recesses 14 and 13 are coveredby the cover 28. In FIG. 3e), a cover for several recesses is combinedwith individual covers, with the recesses 15, 12 and 16 being covered bythe cover 30, while the recesses 14, 13, 11 and 17 are covered by thecorresponding covers 24, 23, 21 and 27. FIG. 3f) finally shows acombination of individual covers, covers for a plurality of recesses,and non-covered recesses. Thus, as in FIG. 3e), the recesses 15, 12 and16 are covered by one cover 30, the recesses 14 and 13 are covered bythe corresponding individual covers 24 and 25, while the recesses 11 and17 remain uncovered. In general, covers for any number of recesses canbe combined in any desired manner with individual covers as well as withnon-covered recesses.

[0074] The covers are not limited to an upper surface 18 of the carrier10, and can project laterally beyond the cover 10.

[0075] As with the cover 10, at least one of the covers shown in theFIG. 3 can be made of graphite, sapphire, quartz, boron nitride,aluminum nitride, silicon, silicon carbide, silicon nitride, ceramic ormetal. However, not only the carrier 10 but also at least one of thecovers can also be made of the aforementioned materials.

[0076] For RTP processes, one advantageously selects carriers 10 havingat least one cover that has a low specific thermal capacity of thecarrier and/or of at least one cover. The thermal capacity is preferablybetween 0.8 J/gK and 0.2 J/gK. For this reason, the carrier 10 shouldhave as small a thickness as possible that does not exceed 5 mm. Acarrier thickness of up to 3 mm is preferred.

[0077] Similarly, carriers 10 having at least one cover are advantageouswhere the carrier 10 and/or at least one of the covers has a highthermal conductivity. The thermal conductivity is preferably between 10W/mK and 180 W/mK.

[0078] The covers can, as the cover 33 shown in FIG. 4a), be placed uponthe carrier 10 and cover the recess 32 with the wafer 2 disposedtherein. The cover 33 is preferably provided with knob-shaped formations34 or similar corresponding devices that fit precisely in correspondingdepressions 35 on the upper surface 18 of the carrier 10 and fix thecover 33 in place to prevent it from slipping. However, such devices canalso be dispensed with.

[0079] Preferred is an embodiment where the recess 32, as shown in FIG.4b), is provided with an indentation 36 that surrounds it in the mannerof a ring and in which the cover 33 is accommodated. The depth of theindentation 36 is advantageously the same as the thickness of the cover33 in order to provide a flushness with the upper surface 18 and toensure a planar upper surface of the carrier 10. At least portions ofthe carrier 10, or portions of one of the covers 20 to 31, or portionsof the carrier 10 and portions of at least one of the covers 20 to 31,are advantageously coated. Thus, for example, it can be advantageous toprovide an inner surface of one or of all of the recesses 11 to 16, aswell as a surface of one or more covers 20 to 31 that cover the recess,at least partially with a specific layer that is inert to chemicalprocesses that occur while processing the wafer 3 within the coveredrecess 11 to 16, while external surfaces of the carrier 10 remainuncoated in order to exhibit desired absorption characteristics relativeto the heat radiation. In other cases, for example local opticalcharacteristics of the carrier 10 and the covers 20 to 31 can beachieved by suitable coating of regions of the outer surfaces.

[0080] Similarly, it can be advantageous if at least portions of thecarrier 10, or portions of one of the covers 20 to 31, or portions ofthe carrier 10 and portions of one of the covers 20 to 31, aretransparent for the heat radiation by making them, for example, ofquartz or sapphire. The covers 20 to 31 as well as parts of the carrier10 that correspond to the base surfaces of the recesses, areadvantageously non-transparent for the heat radiation, while the otherparts of the carrier 10 are transparent.

[0081] In a preferred embodiment of the carrier 10, all of the recesses20 to 31 have the same depth. In this way the loaded wafers 2 have aparallel orientation and are all in one plane and at the same height.

[0082] However, it can sometimes also be advantageous for the depths ofthe recesses 20 to 31 to differ. In this case, although the wafers 2 arealways still parallel, they are offset from one another in height andare disposed at various planes.

[0083] A support of the wafers 2 is advantageously selected within atleast one of the recesses 11 to 17 to avoid a contact between the waferand the base of the recess. As shown in FIG. 5a), this is advantageouslyachieved by pin-shaped support elements 37 that are disposed within arecess 32 and by which the wafer 2 is accommodated. With recesses havingthe same depth but with different lengths of support elements 37, thewafers 2 can then be disposed at different planes in each recess.

[0084]FIG. 5b) shows another preferred possibility for disposing thewafer 2 in such a way that a contact with a base of the recess 32 isavoided. Here the wafer 2 is supported in its rim region in that therecess 32 tapers conically inwardly. In this way there is achieved aninwardly beveled edge of the recess 32 that enables a rim support of thewafer.

[0085] With another embodiment shown in FIG. 5c), a recess 32 isconcavely configured, which again leads to a supporting of the rim ofthe wafer 2 upon the edge of the recess 32. Depending upon the design ofthe conical and of the concave recesses 32, one can place the wafers atdifferent heights.

[0086] To load the carrier 10, a gripper is utilized that operates, forexample, via a suction device, for example according to the Bernoulliprinciple. This gripper successively receives the wafers 2 and placesthem into the recesses 11 to 17.

[0087] Pursuant to another embodiment, the wafers 2 are placed uponsupport pins 38, as shown in FIG. 6a). The support pins 38 are guidedthrough bores 39 that are provided in the base of each recess 32.Similarly, the covers 33 can be disposed on support pins 40. The supportpins 40 are either guided through the bores 41, as illustrated in FIG.6a) and that extend through the carrier 10 beyond the recesses 32, orthe support pins 42 extend entirely externally of the carrier 10. Thesupport pins 38 advantageously have different heights for differentrecesses in order not to hinder a loading of the recesses that areremote from the gripper by the support pins that are provided forloading the recesses that face the gripper. For the same reasons, thesupport pins 40 for the covers 33 can have different lengths. Thesupport pins 40 are preferably all higher than are the support pins 38.

[0088] Pursuant to another embodiment, the carrier 10 is rotated about avertical axis for the loading. In this way, the recess 32 that is to beloaded at any given time can always face the gripper.

[0089] As soon as the wafers 2 are placed upon the support pins 38, andthe covers 33 are placed upon the support pins 40, these pins are moveddownwardly through the carrier 10, as a result of which the wafers 10are raised from the support pins 38, and the covers 33 are raised fromthe support pins 40. The wafers 2 are thereby placed into the recessesassociated with them. Alternatively, the carrier 10 can also be movedupwardly.

[0090] The loading of the wafer 10 can be effected not only within theprocess chamber 4, but also externally of the process chamber 4.

[0091] The transport arm 41, which is illustrated in FIGS. 7 and 8, ofthe inventive handling apparatus, as is used, for example, inconjunction with the handling of wafers and receptacles during thermaltreatment processes, typically has a width b of approximately 35 mm,which is less than the diameter of an object, for example a wafer 42 ora receptacle, that is illustrated in dashed lines. In this way, thewafer, which is stacked and accommodated in cassettes such that it isspaced from adjacent wafers, can be removed from the cassettes and afterthe processing can again be placed therein. The thickness d (see FIG. 8)of the transport arm 41 is in the range of 1 to 5 mm, and is typically 2mm. The thickness is such that the transport arm 41 fits between twoadjacent wafers that are disposed in the cassettes, and can hence removea wafer 42 from the cassette. The length of the transport arm 41 isselected in conformity with the requirements, and the same is true withthe cross-sectional and thickness profile. The typical length of atransport arm 41 in the aforementioned embodiment is between 20 and 70cm.

[0092] Pursuant to the embodiment illustrated in FIGS. 7 and 8, thewafer is supported by three support devices 43-1, 43-2, 43-3, which arealso known as pads, and which in the illustrated embodiment are alsoprovided for the support of a (not-illustrated) receptacle.Alternatively, it is also possible to provide different support devicesor pads for the wafers on the one hand and the receptacle on the otherhand.

[0093] Provided in the transport arm 41 are vacuum or underpressurelines 44 that connect the pads 43-1, 43-2, 43-3 with a vacuum orunderpressure source 45 via a connecting line 46. Provided in one vacuumline 44 to one of the pads 43-2 is a vacuum control element 47, forexample a controllable valve.

[0094] The transport arm 41 is connected via a securement element 48with non-illustrated components and movement elements of the handlingdevice. Similarly extending in the securement element 48 are vacuumlines or channels 49, those ends of which face away from the transportarm being connected to the connecting line 46.

[0095] As already described previously in detail, the pads 43-1, 43-2,and 43-3 can have shapes, masses and designs that are adapted inconformity to the conditions in order to reliably support the wafer aswell as the receptacle that is to be handled.

[0096] Pursuant to a further embodiment of the invention, the vacuumcontrol element 47 is adapted to apply a vacuum to one of the pads thatdiffers from that applied to the remaining pads, if this is necessary.

[0097] In addition, individual vacuum control elements can berespectively provided for each of the pads. A vacuum control device 51can be provided in the connecting line 46, for example between thetransport arm 41 and the underpressure or vacuum source 45. Oneembodiment for this is schematically illustrated in FIG. 9. In theconnecting line 46, between the vacuum source 45 and the vacuum lines 44of the transport arm 41, two parallel vacuum lines 52 and 53 areprovided in the vacuum control device 51 and can be selectively switchedinto the vacuum line 46 via a first and a second change-over switch 54,55. The first vacuum line 52 serves for conveying the vacuum madeavailable from the vacuum source 45 without change to the vacuum lines44 of the transport arm 41. In contrast, provided in the second vacuumline 53 of the vacuum control device 51 is a vacuum regulator 56 thatalters the vacuum in the second connecting line 53.

[0098] In the illustrated embodiment the switching of the change-overswitches 54 and 55 is effected via a computer that is controlled byinstruction software and is schematically provided with the referencenumeral 57 and makes available to an interface 58 of the vacuum controldevice 51 the appropriate program instructions, which then pass in theform of control signals to the change-over switches 54 and 55 viaelectrical lines 59 and 60.

[0099] Instead of controlling the change-over switches 54 and 55 bymeans of a program, it is also possible to control the switching of theoutput signal of the weight sensor that detects the weight of the objectthat is to be handled.

[0100] With an object 42 that is to be handled that has a relativelyhigh weight, a relatively high vacuum, i.e. a relatively small absolutepressure, is applied to the support devices 43-1, 43-2, 43-3 in that thefirst vacuum line 52, which does not have a vacuum regulator, isconnected with the vacuum source 45 via the switch position of thechange-over switches 54 and 55 illustrated in FIG. 9. In the case of thetemperature treatment of wafers, this object—as previously described indetail—is a receptacle in which at least one wafer is contained, andwhich, for example, is made of graphite, silicon carbide or aluminumnitride.

[0101] Such a receptacle of graphite can, pursuant to furtherembodiments, also be coated with the materials silicon carbide oraluminum nitride. Due to the relatively high vacuum, the receptacle issecurely and reliably pressed against and held on the support device viathe pads 43-1, 43-2, 43-3 during the handling and transport process.

[0102] If, however, with the same handling apparatus an object having alesser weight, for example a semiconductor wafer having a weight of 0.1to 20 g, is to be transported or handled, the change-over switches 54and 55 are switched over into the position in which the pads 43-1, 43-2,and 43-3 communicate with the pressure source 45 via the secondconnecting line 53. In this second connecting line 53, the vacuum isreduced by the vacuum regulator 56, in other words the absolute pressureis increased, so that the application pressure is less for the waferthan for the receptacle. This vacuum is thus adapted to the wafer and isso low that the danger of breakage due to too great of a vacuum at thepads is prevented.

[0103] In FIGS. 10a and 10 b an embodiment is illustrated for atransport arm 41 that has a respective support apparatus on both sidesthat can differ from one another, for example, with regard to the numberof pads 61-1, 61-2, 61-3, 62, the structure thereof, the form thereofand/or the dimensions thereof. Whereas in FIG. 10a a pad structure isillustrated that essentially corresponds to the embodiment of FIG. 7,and is provided for supporting objects having little weight, for examplewafers, the other side of the transport arm 41 has a pad structure that,for example, has only one relatively large surfaced, round pad that isconnected to only one vacuum line and is provided, for example, for anobject having a high weight, for example for a wafer receptacle or agraphite box.

[0104] As indicated by the arrow of rotation 63, with this embodimentthe transport arm 41 can be rotated about its axis 64 by 180°, so thatdepending upon whether the object with great weight or the object withlesser weight is to be supported and handled, one of the two side of thetransport arm 41 can be selectively used.

[0105] If the handling apparatus is used in the semiconductor industry,the material thereof, and in particular the material of the transportarm 41, should be suitable for this application, and preferablycomprises sapphire, ceramic and/or quartz, of a combination of thesematerials. These materials furthermore have the advantage that theloading and unloading of a process chamber can be effected attemperatures of up to 700° C. Due to the high modulus of elasticity,sapphire and ceramic also have the further advantage of a high rigidity,i.e. the transport arm 41, even if a receptacle having a weight of 200 gis placed thereupon, bends or bows only slightly, if at all. The surfaceof the transport arm 41 should be as smooth as possible. This, and asunitary a design of the transport arm 41 as possible, facilitates thecleaning and reduces a possible transport of particles into the processchamber.

[0106] Although the invention was described with the aid of preferredembodiments, it is not limited to the concrete embodiments. For example,the carrier 10 can have an angled shape. Similarly, the recesses canhave an angular shape. In addition, the number of recesses is notlimited to seven. Also with carriers having round recesses the diameterof the recesses can differ from 52 mm in order to also be able toaccommodate wafers of 100 mm or 150 mm. A carrier can, for example, alsohave recesses having different dimensions. Furthermore, individualfeatures of the above described embodiments can be combined or exchangedwith one another in any compatible manner.

[0107] The inventive handling apparatus is also not limited to thefeatures and design of the described embodiments. For example it is alsopossible to support the objects, for example, the wafers or receptacles,on the support devices in such a way that the suction is effected viathe Bernoulli effect, in other words, in that vacuum is supplied to theholding devices or pads, so that a Bernoulli effect results. In thiscase, acceleration forces in the horizontal direction must be providedvia additional auxiliary means, which, for example, can be edgeboundaries via which the objects can be fixed in position relative tothe transport arm 41.

1. Device for accommodating disk-shaped objects, preferablysemiconductor wafers, for the thermal treatment thereof, characterizedby a carrier having at least two recesses respectively receiving anobject.
 2. Device according to claim 1, characterized by at least onecover for covering at least one recess.
 3. Device according to claim 1or 2, characterized in that the carrier and/or at least one of thecovers is made of graphite, sapphire, quartz, boron nitride, aluminumnitride, silicon, silicon carbide, silicon nitride, ceramic and/ormetal.
 4. Device according to one of the preceding claims, characterizedin that the carriers and/or the covers have a thermal capacity between0.2 J/gK and 0.8 J/gK.
 5. Device according to one of the precedingclaims, characterized in that the carrier and/or the covers have athermal capacity between 10 W/mK and 180 W/mK.
 6. Device according toone of the preceding claims, characterized in that at least parts of thecarrier and/or of the covers are coated.
 7. Device according to one ofthe preceding claims, characterized in that at least portions of thecarrier and/or of the covers are transparent.
 8. Device according to oneof the preceding claims, characterized in that gas atmospheres thatdiffer from one another are provided in the individual recesses. 9.Device according to one of the preceding claims, characterized in thatthe objects are disposed in one plane.
 10. Device according to one ofthe preceding claims, characterized in that the objects are disposed inat least two planes that are parallel to one another and are spaced fromone another.
 11. Device according to claim 10, characterized in that atleast two recesses have different depths.
 12. Device according to one ofthe preceding claims, characterized in that at least one object restsflat upon a base surface of the recess.
 13. Device according to one ofthe claims 1 to 10, characterized in that at least one object is spacedfrom the base surface of the recess.
 14. Device according to claim 13,characterized in that at least one object rests upon support elements.15. Device according to claim 13, characterized in that at least oneobject rests in its edge region.
 16. Device according to one of thepreceding claims, characterized in that at least one recess has aconical configuration in at least its outer region.
 17. Device accordingto one of the preceding claims, characterized in that at least onerecess has a concave configuration.
 18. Device according to one of thepreceding claims, characterized in that at least two recesses havedifferent dimensions.
 19. Device according to one of the precedingclaims, characterized in that at least two of the objects have differentdimensions.
 20. Device according to one of the preceding claims,characterized in that the objects are combination semiconductors. 21.Device according to one of the preceding claims, characterized in thatat least two of the objects have different materials.
 22. Deviceaccording to one of the preceding claims, characterized in that theobjects are at least partially coated.
 23. Device according to one ofthe preceding claims, characterized in that the object material isnon-homogeneous.
 24. Device according to one of the preceding claims,characterized by support pins for the loading of the carrier withobjects and/or covers.
 25. Device according to claim 24, characterizedin that the support pins pass through the carrier.
 26. Device accordingto claim 24 or 25, characterized in that the pins have differentheights.
 27. Device according to one of the claims 24 to 26,characterized in that the support pins for the covers are higher thanfor the objects.
 28. Device according to one of the claims 24 to 27,characterized in that at least one support pin for the covers isprovided externally of the carrier.
 29. Device according to one of theclaims 24 to 28, characterized in that the carrier and the support pinsare movable relative to one another in the vertical direction. 30.Device according to claim 29, characterized in that the support pins aremovable vertically downwardly for the placement of the objects into therecesses and/or for the placement of the covers upon the carrier. 31.Device according to claim 29, characterized in that the support pins aremovable vertically upwardly for raising the objects out of the recessesand/or for raising the covers from the carrier.
 32. Device according toclaim 29, characterized in that the carrier is movable vertically. 33.Device according to one of the preceding claims, characterized by agripper having suction devices for the deposit of the objects into therecesses and/or upon the support pins, and/or for the removal of theobjects from the recesses and/or from the support pins.
 34. Deviceaccording to one of the preceding claims, characterized by a rotarydevice for the rotation of the carrier about a vertical axis.
 35. Deviceaccording to one of the preceding claims, characterized in that thecarrier can be loaded within a process chamber.
 36. Device according toone of the preceding claims, characterized in that the carrier can beloaded externally of the process chamber.
 37. Device according to one ofthe preceding claims, characterized by an automatic loading andunloading device.
 38. Handling apparatus having at least one transportarm that is provided with at least one support device for the support,via vacuum, of at least one object that is to be handled, characterizedby a vacuum control device for the alteration of the vacuum as afunction of the weight of the object.
 39. Handling apparatus accordingto claim 38, characterized in that the vacuum control device includes avacuum source and vacuum change-over devices.
 40. Handling apparatusaccording to claim 38 or 39, characterized in that the vacuumchange-over device is provided with switches for the change-over betweenlines with and without vacuum regulators.
 41. Handling apparatusaccording to one of the claims 38 to 40, characterized in that thevacuum control device has at least two separate vacuum systems. 42.Handling apparatus according to one of the preceding claims,characterized in that the vacuum ratio for the objects that are to behandled and that have different weights is in a range of from 10 to10,000.
 43. Handling apparatus according to one of the claims 38 to 42,characterized in that an object with lesser weight is a semiconductorwafer, and an object with greater weight is a semiconductor waferreceptacle.
 44. Handling apparatus according to one of the claims 38 to43, characterized in that the support device is differently embodied forthe different objects.
 45. Handling apparatus according to one of theclaims 38 to 44, characterized in that a three-point support device isprovided.
 46. Handling apparatus according to one of the claims 38 to45, characterized in that support devices are provided on both sides ofthe transport arm.
 47. Handling apparatus according to claim 38 to 46,characterized in that one side of the transport arm has support devicesfor the object with greater weight, and its other side has supportdevices for the object of lesser weight.
 48. Handling apparatusaccording to claim 46 or 47, characterized in that the transport arm isrotatable about 180° relative to its longitudinal axis.
 49. Handlingapparatus according to one of the claims 38 to 48, characterized in thatat least two transport arms are provided, of which at least one isprovided for the support of objects having greater weight and at leastone further one is provided for the support of objects of lesser weight.50. Handling apparatus according to one of the claims 38 to 49,characterized in that the vacuum control device is controllable as afunction of a prescribed program sequence.
 51. Handling apparatusaccording to one of the claims 38 to 50, characterized by a sensor thatmeasures the weight of the object that is to be handled, and with theoutput signal of which the vacuum control device can be controlled.